Hi Sarah that is one impressive greenhouse,I grew Malabar spinach this year in my polytunnel..What a plant, I planted 5 seedlings on a 5 cane wig-wam and away it went.It’s not a true spinach but it does taste similar only a bit fleshier it fed 4 families,I just trained it along the crop bars via twine.
You can get it from Bingenheimer (link provided) The postage is a bit pricey so make sure you order some more of their wonderful seeds..
I can personally recommend.
Florence fennel Perfektion they grew to 750g for me.
Carrots Robila excellent germination and flavour.
Melon Murmel gorgeous flavour.
Kohlrabi Superschmelz the only one I grow now,I grow them in the Autumn (planted late summer) they get pretty
big but never stringy..
https://seeds.bingenheimersaatgut.de/info/en/about-us/about-us.html